CN109207961B - Tubular furnace and method for preparing graphene/hexagonal boron nitride heterojunction by using same - Google Patents

Tubular furnace and method for preparing graphene/hexagonal boron nitride heterojunction by using same Download PDF

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CN109207961B
CN109207961B CN201811238729.7A CN201811238729A CN109207961B CN 109207961 B CN109207961 B CN 109207961B CN 201811238729 A CN201811238729 A CN 201811238729A CN 109207961 B CN109207961 B CN 109207961B
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CN109207961A (en
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李雪松
侯雨婷
贾瑞涛
青芳竹
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University of Electronic Science and Technology of China
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
    • C23C16/34—Nitrides
    • C23C16/342—Boron nitride
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
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Abstract

The invention discloses a tubular furnace and a method for preparing a graphene/hexagonal boron nitride heterojunction by using the tubular furnace. The tube furnace comprises a furnace body and a furnace tube, wherein two heating units are arranged in the furnace body, and the furnace tube comprises an inner tube and an outer tube which penetrate through the two heating units; the quartz boat is placed to inside one end of inner tube, and the through-hole that is used for settling the basement is seted up to the other end, and quartz boat and through-hole are just to two heating units respectively. When the heterojunction is prepared, a copper foil is placed at a through hole on an inner tube, a nitrogen-boron source is firstly introduced into the inner tube to form a hexagonal boron nitride film on the lower surface of the copper foil, after a continuous hexagonal boron nitride film is formed, a carbon source is introduced into the outer tube, the carbon source forms a graphene layer on the upper surface of the copper foil and diffuses to the lower surface of the copper foil through the copper foil, and background graphene is formed between the copper foil and the boron nitride film to finish the preparation of the heterojunction. By adopting the tube furnace and the preparation method, the problems of poor heterojunction quality and poor controllability of the growth process can be effectively solved.

Description

Tubular furnace and method for preparing graphene/hexagonal boron nitride heterojunction by using same
Technical Field
The invention belongs to the technical field of heterojunction preparation, and particularly relates to a tube furnace and a method for preparing a graphene/hexagonal boron nitride heterojunction by using the tube furnace.
Background
The preparation of the conventional heterojunction mainly comprises the following two methods, one method is that a graphene heterojunction is constructed by layer-by-layer transfer, a layer of graphene is transferred on a target substrate, and then a layer of hexagonal boron nitride is transferred on the graphene, or the hexagonal boron nitride is transferred layer-by-layer in an opposite sequence; according to this method, the heterojunction preparation cost is high, and environmental factors and mechanical damage during the transfer process can seriously affect the quality of the heterojunction. The other method is to directly form a film on a substrate on which a film is grown by Chemical Vapor Deposition (CVD), prepare a hexagonal boron nitride film on a copper foil on which graphene has been grown by CVD, or prepare a graphene/hexagonal boron nitride heterojunction in the reverse order. The latter method can reduce the influence of environmental factors and mechanical damage, but the growth process has poor controllability.
Disclosure of Invention
Aiming at the prior art, the invention provides a tube furnace and a method for preparing a graphene/hexagonal boron nitride heterojunction by using the tube furnace, so as to solve the problems of poor heterojunction quality and poor controllability in a growth process.
The tube furnace comprises a furnace body and a furnace tube, wherein a first heating unit and a second heating unit are respectively arranged at two ends of the furnace body, the central distance between the first heating unit and the second heating unit is 30-50 cm, the furnace tube penetrates through the first heating unit and the second heating unit and extends out of the furnace body, one end of the furnace tube is communicated with an air source through a flowmeter, and the other end of the furnace tube is communicated with a vacuum pump; the furnace tube comprises an inner tube and an outer tube, the inner tube and the outer tube are hollow tubes, the inner tube is positioned in the outer tube, and a gas channel is formed between the inner tube and the outer tube; the quartz boat is placed to inside one end of inner tube, and the through-hole that is used for settling the basement is seted up to the other end, and quartz boat and through-hole are just to first heating unit and second heating unit respectively.
The method is based on a diffusion theory, and carbon source concentration difference is formed on two sides of the copper foil, so that the carbon source is diffused from one side to the other side to form graphene on the back bottom, and the quality of the heterojunction can be greatly improved. The preparation method comprises the following steps:
s1, placing the polished copper foil at the through hole on the tube in the tube furnace, and annealing the copper foil;
s2, controlling the temperature of the copper foil to be more than 1000 ℃, introducing diffusion gas into the inner tube, heating the nitrogen and boron source in the quartz boat to decompose the nitrogen and boron source, driving the decomposed nitrogen and boron source to diffuse to the copper foil by the diffusion gas, and cracking the lower surface of the copper foil to form a hexagonal boron nitride film;
s3, after obtaining the continuous boron nitride film, keeping the temperature of the gas and the copper foil introduced into the inner tube unchanged, introducing a carbon source into the outer tube, cracking the carbon source on the surface of the copper foil to form a graphene layer, diffusing the graphene layer to the other side through the copper foil, and forming background graphene between the copper foil and the hexagonal boron nitride film; and when the graphene layer on the upper surface of the copper foil is not regenerated for a long time, stopping heating and rapidly cooling the copper foil to room temperature to finish the preparation of the heterojunction.
Specifically, the copper foil annealing treatment method comprises the following steps: placing the copper foil at the through hole, pumping the furnace tube until the background vacuum value is 0.25-0.3 pa, and then introducing Ar and H into the inner tube2Introducing Ar or H into the outer tube2And raising the temperature of the copper foil to 1010-1060 ℃ within 0.5-1 h, preserving the temperature for 0.5-3 h, and annealing for 20-30 min.
Wherein the flow rate of Ar in the inner tube is 50-400 sccm, H2The flow rate of (2) is 5-60 sccm; ar or H in the outer tube2The flow rate of (2) is 10 to 100 sccm.
The copper foil used in the invention is firstly polished, and the polishing method comprises the following steps: and clamping the copper foil by using an anode and soaking the copper foil into an electropolishing solution, wherein the electropolishing solution comprises 200mL of phosphoric acid, 100mL of ethylene glycol and 100mL of acetic acid, the other copper foil is used as a cathode, the voltage is applied for 2.7V, the copper foil is polished for 30min, and the copper foil is taken out and washed by deionized water to finish polishing. The polished copper foil is trimmed to the same shape and size as the through-hole on the inner tube, and placed at the through-hole, followed by annealing. In the invention, during annealing, gases with different types and flow rates are introduced to the two sides of the copper foil, so that organic matters and oxides attached to the surface of the copper foil are removed, and recrystallization in different degrees can be carried out on the two sides of the copper foil, thereby being beneficial to the growth of subsequent hexagonal boron nitride (h-BN) and the permeation of a carbon source.
Specifically, the method for forming the hexagonal boron nitride film comprises the following steps: after the copper foil is annealed, heating the copper foil to 1010-1060 ℃, and introducing 1-15 sccm of H into the inner pipe2And Ar of 10-100 sccm, introducing Ar of 10-100 sccm into the outer tube, heating the quartz boat to 60-130 ℃ to decompose the nitrogen and boron source in the quartz boat, wherein the decomposed nitrogen and boron source is introduced with H2And diffusing the hexagonal boron nitride film and Ar to the copper foil, and cracking and depositing the hexagonal boron nitride film on the copper foil to form the hexagonal boron nitride film.
Wherein the nitrogen boron source is borane ammonia complex, and the decomposition temperature is 120 ℃.
When the hexagonal boron nitride film is formed, the temperature of the copper foil is 10 DEG50 ℃ in the inner tube H2The flow rate of Ar is 10sccm, the flow rate of Ar is 50sccm, and the flow rate of Ar in the outer tube is 50 sccm.
In the present invention BH is preferably employed3NH3As a source of boron nitrogen, BH3NH3Decomposing at 110-130 ℃, wherein the nitrogen-boron source is rapidly decomposed into hydrogen, polyimidinediborane and borazine at the temperature, and the decomposition process is shown as the formula (1):
Figure BDA0001838791270000031
the decomposed borazine continuously diffuses to the copper foil, a plurality of nucleation points are formed on the surface of the copper foil, and the h-BN film is formed through the processes of dehydrogenation, nucleation, growth and the like.
In the process of forming the H-BN film, H is introduced into the inner tube2And Ar is introduced into the outer tube, the upper surface of the copper foil can be kept clean by the Ar in the inner tube and the outer tube, and the pressure on two sides of the copper foil is maintained, so that the h-BN film can grow on the lower surface of the copper foil quickly. H introduced into the inner tube2The flow rate of the precursor is preferably 10sccm, and the precursor can be rapidly guided to the surface of the copper foil to participate in the reaction without being taken out of the inner tube, so that the waste of the precursor is avoided, and H is realized at the moment2The method has the greatest promotion effect on the dehydrogenation reaction of borazine on the surface of the copper foil, and can accelerate the growth of the h-BN film.
When the h-BN film grows, the temperature of the copper foil is controlled within the range of 1010-1060 ℃, the copper foil has the strongest catalytic activity within the temperature range, the decomposition efficiency of borazine is the highest, the nucleation density of h-BN is increased, the grain size is increased, and the formed h-BN film is better and uniform.
Specifically, the method for forming the graphene layer and the back graphene comprises the following steps: after introducing a nitrogen and boron source for 0.5-2 h, keeping the temperature of the copper foil at 1010-1060 ℃, continuously introducing the nitrogen and boron source into the inner tube, and introducing 10-100 sccm CH into the outer tube4And H of 10 to 100sccm2(ii) a Introduction of CH4Stopping heating after 30-90 min, and cooling the copper foil to room temperature within 0.5-1 h to ensure that the copper foil is coveredA graphene layer is formed on the surface, and background graphene is formed between the lower surface of the copper foil and the hexagonal boron nitride film.
When the graphene layer and the back bottom graphene are formed, the temperature of the copper foil is 1050 ℃, and CH is introduced4And H2The flow rate of (2) is 50 sccm.
According to the invention, the carbon source is introduced into the outer pipe and the nitrogen boron source is introduced into the inner pipe, the concentration difference of the carbon source is formed on two sides of the copper foil, and CH is generated due to the concentration difference4The cracked carbon atoms (active groups) can permeate from the upper surface of the copper foil to the lower surface of the copper foil, and the specific process is as follows: CH (CH)4As a carbon source, it follows H2Diffusing to the copper foil together, adsorbing and cracking on the surface of the copper foil, dissociating the cracked carbon atoms on the surface of the copper foil and permeating into the copper foil, diffusing the carbon atoms in the copper foil to the other side of the copper foil, mutually gathering the carbon atoms on two sides of the copper foil to form clusters, and forming a graphene crystal nucleus when the size of the clusters exceeds a critical size; with continuous adsorption and cracking of a carbon source, a graphene crystal domain grows; introduction of CH4After 30-90 min, the upper surface of the copper foil starts to be covered by graphene, active catalysis on a carbon source is gradually lost, the graphene stops growing, after the upper surface of the copper foil is completely covered by the graphene, the copper foil stops being heated, the temperature of the copper foil is rapidly reduced to room temperature, the solubility of carbon in the copper foil is reduced along with the reduction of the temperature, the carbon is supersaturated in dissolution, carbon atoms are separated out, a graphene layer is formed on the upper surface of the copper foil, and background graphene is formed between the copper foil and the hexagonal boron nitride film.
The invention introduces H while introducing the carbon source2And H is2The flow rate of (A) is preferably the same as that of the carbon source, because, under the condition, the hydrogen partial pressure is moderate, the hydrogen partial pressure can promote the penetration of carbon atoms in the copper foil while introducing more carbon source to the surface of the copper foil to participate in the reaction, and the temperature of the copper foil is about 1050 ℃ at the moment, the hydrogen partial pressure is not only the same as that of the carbon source, but also the carbon source can not only be used for treating CH4Has better cracking effect, and larger gaps are formed among copper atoms, which is beneficial to the penetration of carbon atoms on the upper surface of the copper foil to the lower surface.
The invention has the beneficial effects that:
1. the method can be used for preparing the high-quality hexagonal boron nitride film and realizing the preparation of the large-area high-quality hexagonal boron nitride film.
2. Obtaining a process for growing the hexagonal boron nitride film on the single side of the copper foil substrate; the method lays a foundation for the preparation and application of the graphene/hexagonal boron nitride heterojunction film;
3. the hexagonal boron nitride and the graphene are directly grown on the surface of the metal, and the high quality of the hexagonal boron nitride and the graphene is kept.
4. Avoiding mechanical damage to the transfer process.
Drawings
FIG. 1 is a front view of a tube furnace according to the present invention; wherein, 1, a furnace body; 11. a first heating unit; 12. a second heating unit; 2. a furnace tube; 21. an outer tube; 22. an inner tube; 23. a quartz boat; 24. a through hole; 3. a flow meter; 4. a vacuum pump.
FIG. 2 is a diagram of the heterojunction formation mechanism of the present invention;
fig. 3 is a diagram illustrating a mechanism of forming a graphene layer and underlying graphene.
Detailed Description
The quality of the heterojunction is seriously influenced due to mechanical damage when the graphene heterojunction is constructed by adopting a layer-by-layer transfer method; and the film is directly prepared by adopting a chemical vapor deposition method, and the controllability of the growth process of the film is poor. In order to solve the problems, the invention provides a novel heterojunction preparation method, and in order to successfully implement the method, the invention also designs a tubular furnace with a novel structure. As shown in figure 1, the tube furnace comprises a furnace body 1 and a furnace tube 2, wherein two temperature zones are arranged in the furnace body 1, namely a first heating unit 11 and a second heating unit 12 are respectively arranged on two sides in the furnace body 1, the first heating unit 11 and the second heating unit 12 are the same as those in the conventional tube furnace, and the distance between the first heating unit 11 and the second heating unit 12 is 30-50 cm. The material of the furnace tube 2 is the same as that of a conventional tube furnace, but the structure is changed, the furnace tube 2 comprises an inner tube 22 and an outer tube 21, the inner tube 22 and the outer tube 21 are hollow tubes, the inner tube 22 and the outer tube 21 are concentrically arranged, and a gas channel is formed between the inner tube 22 and the outer tube 21; the main body of the furnace tube 2 passes through the first heating unit 11 and the second heating unit 12, and the two ends of the furnace tube pass through the furnace body1, one end of which is connected with a gas source (H) through a flowmeter 32Source gas, Ar source gas, CH4Air source, etc.) and the other end is communicated with a vacuum pump 4; a quartz boat 23 is arranged at one end inside the inner tube 22, a through hole 24 for placing a substrate is formed at the other end, and the quartz boat 23 and the through hole 24 respectively face the first heating unit 11 and the second heating unit 12.
The method can prepare the high-quality graphene/hexagonal boron nitride heterojunction by utilizing the newly designed tube furnace. The preparation method of the invention is based on the diffusion theory, namely, by creating concentration difference on two sides of the copper foil, substances on one side are diffused to the other side, and a layered structure is formed on the other side, and the heterojunction forming process is shown in figure 2. The method of the invention does not need to transfer the substrate, avoids mechanical damage in the transfer process, and can accurately control the substrate temperature and the precursor flow, so that the preparation of the heterojunction has good controllability. The specific method for preparing the heterojunction comprises the following steps:
s1 copper foil polishing and annealing: clamping the copper foil by using an anode and soaking the copper foil into an electropolishing solution, wherein the electropolishing solution comprises 200mL of phosphoric acid, 100mL of ethylene glycol and 100mL of acetic acid, the other copper foil is used as a cathode, the voltage is applied to 2.7V, polishing is carried out for 30min, and the copper foil is taken out and washed by deionized water to finish polishing; trimming the polished copper foil into a sheet with the same size and shape as the through hole 24 on the inner tube 22, placing the sheet into the through hole 24, connecting air sources and vacuum pumps at two ends of the furnace tube 2, pumping the furnace tube 2 by using the vacuum pump until the background vacuum value is 0.25-0.3 pa, and then introducing Ar and H into the inner tube through the air sources2The flow rate of Ar in the mixed gas is 50-400 sccm, H2The flow rate of (3) is 5-60 sccm, Ar or H is introduced into the outer tube2Ar or H in the outer tube2The flow rate of the copper foil is 10-100 sccm, after the gas flow is stable, the second heating unit 12 is used for heating the copper foil to 1010-1060 ℃, the heating is completed within 0.5-1 h, the heat is preserved for 0.5-3 h at the temperature, and then the annealing is performed for 20-30 min, so that the annealing of the copper foil is completed;
s2 forming a hexagonal boron nitride film by placing a boron nitride source in the quartz boat, heating the boron nitride source in the quartz boat using the first heating unit 11,the decomposition rate of the nitrogen boron source is moderate, the growth rate of the h-BN film is slow due to slow decomposition rate, the waste of the nitrogen boron source is caused due to too fast decomposition rate, and the decomposition temperature of the nitrogen boron source is strictly controlled, for example, the invention adopts the BH of the nitrogen boron hydride3NH3When used as a nitrogen boron source, the decomposition temperature is controlled within the range of 60-130 ℃. Heating the copper foil to a growth temperature of 1010-1060 ℃ while heating the nitrogen-boron source, and simultaneously introducing H with a flow of 1-15 sccm into the inner tube 22 through the gas source2And 10-100 sccm of Ar, introducing 10-100 sccm of Ar into the outer tube 21, and introducing the gas obtained by decomposing the nitrogen-boron source into H2Driven to diffuse towards the copper foil, and is cracked and deposited under the catalysis of the high-temperature copper foil to form a hexagonal boron nitride film on the surface of the copper foil, and after 0.5-2 h, Ar in the outer tube 21 is converted into CH4Growth of graphene and background graphene is started. In the process of forming the hexagonal boron nitride film, Ar in the inner tube and the outer tube maintains the pressure at two sides of the copper foil, so that the hexagonal boron nitride film can only grow on the lower side of the copper foil.
S3, after obtaining the continuous boron nitride film on the lower side of the copper foil, continuously introducing H into the inner tube2And a nitrogen boron source, wherein CH with the flow rate of 10-100 sccm is introduced into the outer pipe4And H of 10 to 100sccm2In which CH4As a carbon source, it follows H2Diffusing to the copper foil together, adsorbing and cracking on the surface of the copper foil, dissociating the cracked active groups on the surface of the copper foil and diffusing to the other side through the copper foil, mutually gathering the active groups on two sides of the copper foil to form clusters, and forming a graphene crystal nucleus when the cluster size exceeds a critical size; with continuous adsorption and cracking of a carbon source, a graphene crystal domain grows; introduction of CH4After 30-90 min, after the upper surface of the copper foil starts to be covered by graphene, the active catalysis on a carbon source is gradually lost, the graphene stops growing, after the upper surface of the copper foil is completely covered by the graphene, the copper foil stops being heated, the solubility of carbon in the copper foil is reduced along with the reduction of the temperature, the carbon is supersaturated in the solution, the graphene is separated out, a graphene layer is formed on the upper surface of the copper foil, and the graphene at the back bottom is formed between the copper foil and the hexagonal boron nitride film. The formation process of the graphene layer and the back graphene is shown in fig. 3。
The method for fabricating the heterojunction in the present invention is described in detail with reference to the following specific examples.
Example one
A preparation method of a graphene/hexagonal boron nitride heterojunction based on a diffusion theory comprises the following steps:
s1, placing the polished copper foil at the through hole on the inner tube of the tube furnace, pumping the tube furnace to a background vacuum value of 0.3pa by using a vacuum pump, and introducing 100sccm Ar and 10sccm H into the inner tube2Introducing Ar of 30sccm into the outer tube, raising the temperature of the copper foil to 1050 ℃ within 1h, and annealing for 30 min;
s2 annealing the copper foil, heating it to 1050 deg.C, and introducing 10sccm H into the inner tube2And 50sccm Ar, introducing 50sccm Ar into the outer tube, heating the quartz boat to 120 ℃ to make BH in the quartz boat3NH3Decomposed, decomposed BH3NH3With introduction of H2And diffusing the hexagonal boron nitride film and Ar to the copper foil, and cracking and depositing the hexagonal boron nitride film on the copper foil to form the hexagonal boron nitride film.
S3, after introducing a nitrogen and boron source for 1h, keeping the temperature of the copper foil at 1050 ℃, continuously introducing the nitrogen and boron source into the inner tube, and introducing 50sccm CH into the outer tube4And 50sccm of H2(ii) a Introduction of CH4And stopping heating after 60min, and cooling the copper foil to room temperature within 1h, wherein a graphene layer is formed on the upper surface of the copper foil, and background graphene is formed between the lower surface of the copper foil and the hexagonal boron nitride film.
Example two
A preparation method of a graphene/hexagonal boron nitride heterojunction based on a diffusion theory comprises the following steps:
s1, placing the polished copper foil at the through hole on the inner tube of the tube furnace, pumping the tube furnace to a background vacuum value of 0.25pa by using a vacuum pump, and introducing Ar of 50sccm and H of 5sccm into the inner tube2Introducing Ar of 10sccm into the outer tube, raising the temperature of the copper foil to 1000 ℃ within 1h, and annealing for 20 min;
s2 annealing the copper foil, heating the copper foil to 1050 ℃, and introducing H of 15sccm into the inner tube2And 100sccm of Ar as a standard,introducing Ar of 100sccm into the outer tube, heating the quartz boat to 60 deg.C to decompose the nitrogen and boron source therein, and introducing H into the decomposed nitrogen and boron source2And diffusing the hexagonal boron nitride film and Ar to the copper foil, and cracking and depositing the hexagonal boron nitride film on the copper foil to form the hexagonal boron nitride film.
S3, after introducing a nitrogen and boron source for 1h, keeping the temperature of the copper foil at 1050 ℃, continuously introducing the nitrogen and boron source into the inner tube, and introducing 100sccm CH into the outer tube4And H of 100sccm2(ii) a Introduction of CH4And stopping heating after 30min, and cooling the copper foil to room temperature within 1h, wherein a graphene layer is formed on the upper surface of the copper foil, and background graphene is formed between the lower surface of the copper foil and the hexagonal boron nitride film.
EXAMPLE III
A preparation method of a graphene/hexagonal boron nitride heterojunction based on a diffusion theory comprises the following steps:
s1, placing the polished copper foil at the through hole on the inner tube of the tube furnace, pumping the tube furnace to a background vacuum value of 0.28pa by using a vacuum pump, and introducing Ar of 200sccm and H of 40sccm into the inner tube2Introducing Ar of 80sccm into the outer tube, raising the temperature of the copper foil to 1050 ℃ within 0.5h, and annealing for 25 min;
s2 annealing the copper foil, heating the copper foil to 1050 ℃, and introducing 1sccm of H into the inner tube2And Ar of 10sccm, introducing Ar of 10sccm into the outer tube, heating the quartz boat to 120 deg.C to decompose the nitrogen and boron source therein, wherein the decomposed nitrogen and boron source is accompanied by introduced H2And diffusing the hexagonal boron nitride film and Ar to the copper foil, and cracking and depositing the hexagonal boron nitride film on the copper foil to form the hexagonal boron nitride film.
S3, after introducing a nitrogen boron source for 1h, keeping the temperature of the copper foil at 1050 ℃, continuously introducing the nitrogen boron source into the inner tube, and introducing CH of 10sccm into the outer tube4And 10sccm of H2(ii) a Introduction of CH4And stopping heating after 90min, and reducing the temperature of the copper foil to room temperature within 1h, wherein a graphene layer is formed on the upper surface of the copper foil, and background graphene is formed between the lower surface of the copper foil and the hexagonal boron nitride film.
Example four
A preparation method of a graphene/hexagonal boron nitride heterojunction based on a diffusion theory comprises the following steps:
s1, placing the polished copper foil at the through hole on the inner tube of the tube furnace, pumping the tube furnace to a background vacuum value of 0.25pa by using a vacuum pump, and introducing Ar of 400sccm and H of 60sccm into the inner tube2Introducing Ar of 100sccm into the outer tube, raising the temperature of the copper foil to 1000 ℃ within 1h, and annealing for 30 min;
s2 annealing the copper foil, heating it to 1050 deg.C, and introducing 10sccm H into the inner tube2And Ar of 10sccm, introducing Ar of 30sccm into the outer tube, heating the quartz boat to 130 deg.C to decompose the nitrogen and boron source therein, wherein the decomposed nitrogen and boron source is accompanied by introduced H2And diffusing the hexagonal boron nitride film and Ar to the copper foil, and cracking and depositing the hexagonal boron nitride film on the copper foil to form the hexagonal boron nitride film.
S3, after introducing a nitrogen boron source for 1h, keeping the temperature of the copper foil at 1050 ℃, continuously introducing the nitrogen boron source into the inner tube, and introducing CH of 30sccm into the outer tube4And 20sccm of H2(ii) a Introduction of CH4And after 80min, stopping heating, and cooling the copper foil to room temperature within 1h, wherein a graphene layer is formed on the upper surface of the copper foil, and background graphene is formed between the lower surface of the copper foil and the hexagonal boron nitride film.
While the present invention has been described in detail with reference to the illustrated embodiments, it should not be construed as limited to the scope of the present patent. Various modifications and changes may be made by those skilled in the art without inventive step within the scope of the appended claims.

Claims (9)

1. A tube furnace, characterized in that: the furnace comprises a furnace body (1) and a furnace tube (2), wherein a first heating unit (11) and a second heating unit (12) are respectively arranged at two ends in the furnace body (1), the furnace tube (2) penetrates through the first heating unit (11) and the second heating unit (12) and extends out of the furnace body (1), one end of the furnace tube is communicated with an air source through a flowmeter (3), and the other end of the furnace tube is communicated with a vacuum pump (4); the furnace tube (2) comprises an inner tube (22) and an outer tube (21), the inner tube (22) and the outer tube (21) are hollow tubes, the inner tube (22) is positioned inside the outer tube (21), and a gas channel is formed between the inner tube (22) and the outer tube (21); a quartz boat (23) is placed at one end inside the inner tube (22), a through hole (24) used for placing a substrate is formed in the other end of the inner tube, and the quartz boat (23) and the through hole (24) are respectively opposite to the first heating unit (11) and the second heating unit (12).
2. A method of preparing a graphene/hexagonal boron nitride heterojunction using the tube furnace of claim 1, wherein the method comprises:
s1, placing the polished copper foil at the through hole on the tube in the tube furnace, and annealing the copper foil;
s2, controlling the temperature of the copper foil to be more than 1000 ℃, introducing diffusion gas into the inner tube, heating the nitrogen and boron source in the quartz boat to decompose the nitrogen and boron source, driving the decomposed nitrogen and boron source to diffuse to the copper foil by the diffusion gas, and cracking the lower surface of the copper foil to form a hexagonal boron nitride film;
s3, after obtaining the continuous boron nitride film, keeping the temperature of the gas and the copper foil introduced into the inner tube unchanged, introducing a carbon source into the outer tube, cracking the carbon source on the surface of the copper foil to form a graphene layer, diffusing the graphene layer to the other side through the copper foil, and forming background graphene between the copper foil and the hexagonal boron nitride film; and when the graphene layer on the upper surface of the copper foil is not regenerated for a long time, stopping heating and rapidly cooling the copper foil to room temperature to finish the preparation of the heterojunction.
3. The method for preparing the copper foil according to claim 2, wherein the specific method of the copper foil annealing treatment is as follows: placing the copper foil at the through hole, pumping the furnace tube until the background vacuum value is 0.25-0.3 pa, and then introducing Ar and H into the inner tube2Introducing Ar or H into the outer tube2And raising the temperature of the copper foil to 1010-1060 ℃ within 0.5-1 h, preserving the temperature for 0.5-3 h, and annealing for 20-30 min.
4. The production method according to claim 3, characterized in that: the flow rate of Ar in the inner tube is 50-400 sccm, H2The flow rate of (2) is 5-60 sccm; ar or H in the outer tube2The flow rate of (2) is 10 to 100 sccm.
5. The production method according to claim 2, wherein the hexagonal boron nitride film is formed by: after the copper foil is annealed, heating the copper foil to 1010-1060 ℃, and introducing 1-15 sccm of H into the inner pipe2And Ar of 10-100 sccm, introducing Ar of 10-100 sccm into the outer tube, heating the quartz boat to 60-130 ℃ to decompose the nitrogen and boron source in the quartz boat, wherein the decomposed nitrogen and boron source is introduced with H2And diffusing the hexagonal boron nitride film and Ar to the copper foil, and cracking and depositing the hexagonal boron nitride film on the copper foil to form the hexagonal boron nitride film.
6. A method according to claim 5, wherein the source of boron nitride is a borane ammonia complex having a decomposition temperature of 120 ℃.
7. The method of claim 5, wherein: the copper foil temperature is 1050 ℃, and H in the inner tube2The flow rate of Ar is 10sccm, the flow rate of Ar is 50sccm, and the flow rate of Ar in the outer tube is 50 sccm.
8. The preparation method according to claim 2, wherein the graphene layer and the underlying graphene are formed by a method comprising: after introducing a nitrogen and boron source for 0.5-2 h, keeping the temperature of the copper foil at 1010-1060 ℃, continuously introducing the nitrogen and boron source into the inner tube, and introducing 10-100 sccm CH into the outer tube4And H of 10 to 100sccm2(ii) a Introduction of CH4And stopping heating after 30-90 min, and reducing the temperature of the copper foil to room temperature within 0.5-1 h, wherein a graphene layer is formed on the upper surface of the copper foil, and background graphene is formed between the lower surface of the copper foil and the hexagonal boron nitride film.
9. The method of claim 8, wherein: the copper foil temperature is 1050 ℃, and CH is introduced4And H2The flow rate of (2) is 50 sccm.
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